This cooperative study involves a number of major medical universities and was designed to test the effectiveness of drug induced hypotension, anti-fibrinolytic therapy, or a combination of both in terms of preventing rebleeding episodes and subsequent mortality from previously ruptured intracranial aneurysms. In both a pilot study and a randomized treatment program, anti-fibrinolytic therapy was found to be statistically superior to the other forms of therapy. On the basis of these studies, the hypotensive and combined therapies were eliminated. Treatment with only anti-fibrinolytic therapy is being continued to evaluate these agents from the standpoint of: optimal dosage; untoward complications related to the therapy and the relationship, if any, of fluid intake and output to the effectiveness of the therapy.